The present invention relates to etching a layer of non volatile materials through a mask during the production of a semiconductor device. More specifically, the present invention relates to etching a metal layers.
During semiconductor wafer processing, features may be etched through a metal layer. In the formation of magnetoresistive random-access memory (MRAM) or resistive random-access memory (RRAM) devices, a plurality of thin metal layers or films may be sequentially etched. For MRAM a plurality of thin metal layers may be used to form metal tunneling junction stacks.
Patterning non-volatile metal materials such as MRAM in a traditional reactive ion etcher (RIE) is challenging due to low volatility of the etch byproducts. The non-volatile sidewall passivation could cause the device short across the magnetic tunneling junction area and degradation of electric performance. Ion Beam Etching (IBE) has been used for MRAM patterning to clean the sidewall and maintain the material integrity. However, IBE is limited by the aspect ratio (<2:1) for advanced technology nodes with high pattern density.